The growth and development of the mammalian uterus is primarily controlled by estrogenic hormones. The proposed research would seek the molecular mechanisms by which estrogenic hormones exert their control. The research is subdivided into two major approaches: 1. Interaction of estrogens with receptor molecules present in the uterine cell; 2. The initial cellular response to the hormone's action. We will concentrate on gaining an understanding of the events related to the movement of the estrogen-receptor complex into the nucleus including transformation or changes in the receptor in the cytoplasm and association with nuclear components. The tissue response studies will concentrate on the regulation of the synthesis of the "induced protein" (IP) of the rat uterus. We are concerned with its characterization and tissue and species distribution. The role of RNA synthesis in regulation of IP synthesis will also be explored.